高分子熔膠微流道流變特性之研究

Study of Polymer Melt Rheological Behavior Flowing Through Micro-Channels

陳嘉濠(Jia-Hao Chen)

指導教授 ： 陳夏宗 ； 蔡瑞益

中原大學/工學院/機械工程研究所/碩士(2003年)

https://doi.org/10.6840/cycu200300303

摘要

中文摘要
隨著塑膠高分子成型技術日益提升，而所生產的零件也日趨微小且精密，運用微射出成型所生產的微機電產品零件需求日益增加。微射出成型中熔膠流過微小尺寸的特性缺乏研究，因此對製程的掌握更增加了不確定性。本論文乃係針對高分子熔膠微流道流動的流變性質進行初步的研究。
研究工作首在建立微流道流變量測系統，並對於熔膠在微流道流變行為上之分析研究。 在微流道流變量測模具上，使用的微流道尺寸分別為0.2 mm、0.3 mm 和0.5 mm之正方形截面流道。實驗中，使用Sodick EH30作為熔膠射出的壓力源和高恆溫模溫機。由量測的壓力差值和流量，經入、出口端的壓力降修正後，可推算出黏度值。
由於實驗之微流道為正方形截面，所以分別使用capillary flow model與slit flow model作計算分析並導入修正因子。 經由分析結果得知，兩模式的所得黏度值相當接近(約2~6%差異)。與傳統毛細流變儀量測值相比，兩模式計算之黏度結果都偏低且隨著管徑的縮小而降低的趨勢。
當微流道的尺寸變小，黏滯熱所造成的影響愈明顯，會造成較大的熔膠溫升。而在經過黏滯熱修正後，管徑0.2 至0.5 mm流道的黏度仍比傳統量測值有一定程度的偏低(約14% ~38% )，因此由初步的探討得知故在微流道中流動時熔膠的黏度相對於大尺寸流道降低。研究結果對於高分子模擬流動軟體的開發與微成型技術層次的推進將提供相當的助益。

關鍵字

流變性質 ； 微射出成型 ； 微流道

並列摘要

Abstract

The micro-parts molded by micro injection molding become more and more popular in MEMS (Micro Electromechanical System) applications. Due to the lack of research in polymer melt flow behavior in micro channels, molding process control exists uncertainties. The purpose of this study is to conduct the investigation on the rheological property of polymer melt flowing through micro-channels.

First, the rheological property measurement system design with micro-channels in a mold was established. Sizes of micro-channel of square cross section used vary from 0.5 mm to 0.3 mm then to 0.2 mm. Sodick EH30 micro injection machine together with a mold temperature control unit as high as 250℃ were utilized to conduct the experiments. From measured flow rate and pressure drop followed by a correction in inlet and outlet pressure drop, the viscosity value can be obtained.

Because of the square cross section of the micro-channels, it is necessary to use capillary flow model and slit flow model to analyze the measured data. The calculated viscosity values are found to be very close from both two models (about 2% to 6% difference). Compared with the measured result from traditional rheometer, viscosity values in micro channel are lower and their value decreases with reducing channel size. With, after correct can permit to calculate the viscosity.

Effect of viscous dissipation is expected to have more influence on viscosity when the micro-channel size becomes smaller. After the correction of the viscous dissipation effect, viscosity values are still lower than the value measured by capillary rheometer (lower by about 14% to 38%). This preliminary founding may be of help to the development of micro-flowing simulation and molding technology promotion.

並列關鍵字

micro-channel ； rheological pro ； micro-injection molding

參考文獻

2 John M.Dealy ,“Polymer Rheology –Challenge For The 21ST Century ”ANTEC 2000

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12 Zehev Tadmor，“Principles of polymer processing ” JOHN WILEY &SONS,(1979) 。